The invention relates to a braiding machine, in particular a circular braiding machine, for braiding a braiding core that is fed in a permanently continuous or pendulous manner, having at least two braiding thread spools and having a braiding ring that is disposed between the braiding thread spools and the run-on point of the braiding threads onto the braiding core. The braiding threads are guided over the internal surface of the braiding ring, and the latter is composed of a plurality of adjustable segments, wherein each adjustable segment of the braiding ring has a dedicated adjustment installation.
In braiding machines, in particular in circular braiding machines, braiding cores which have a cross section that is consistent or changes substantially in the longitudinal direction of the braiding core are often fed in order for the component to be produced to be imparted the later shape thereof.
The braiding cores herein can remain in the later component or be released therefrom as a lost core.
Individual threads or else braiding fibers, for example rovings from carbon or glass fibers, can be used as braiding threads.
So-called preforms which serve for the downstream production of diverse components from fiber-reinforced plastics can be made from these braiding threads or braiding fibers by braiding the latter about a braiding core. It is mandatory herein, with a view to high quality of the later components, that the braiding threads or braiding fibers are deposited onto the braiding core as precisely as possible.
In the case of the conventional braiding procedure, the braiding thread spools are received by bobbins which are moved relative to one another on guide tracks such that a braided product is created. The bobbins herein have dissimilar directions of revolving about the braiding core.
In the case of circular braiding machines, the guide tracks are two concentric circular paths that move in opposite directions, the braiding core to be braided moving in the center of said paths so as to be axially offset. It is thus achieved that the braiding threads or braiding fibers of the bobbins in the positive direction of rotation continuously cross those of the negative direction of rotation such that a circular braided product is configured as a braided core is braided.
If braided cores having a complex core geometry are used in the braiding machines, a uniform braided structure cannot be achieved by way of the usually round braiding rings with a constant opening cross section.
Differences, which in some instances are significant in terms of the local braiding angle, the layer thickness, and the thread density on the individual sides of the braiding core, are created when rigid braiding rings having a round opening cross section are used, even in the case of braiding core cross sections having very dissimilar lateral lengths.
Furthermore, in the case of curved braiding cores, dissimilar braided structures are created on the internal and the external radius of the curvature when the known rigid braiding rings having a round opening cross section are used.
In order to redress this, DE 10 2010 047 193 A1 describes a circular braiding machine which has a braiding ring made from four angled segments which can all be simultaneously displaced radially toward the braiding core or away from the latter by the same displacement path. The individual segments mutually overlap on the free ends thereof. The adjustment installations engage in the angled region thereof.
This arrangement has the disadvantage that the individual segments of the braiding ring can follow changes in the cross section of the braiding core only when said changes run symmetrically to the longitudinal axis of the braiding ring. Local convexities or concavities, respectively, of the braiding core cannot be followed, such that the quality of the braided product is compromised. Likewise, braiding cores having very dissimilar lateral lengths cannot be braided with adequate quality.
Another solution is known from U.S. Pat. No. 6,679,152 B 1. Here, at least one adjustable braiding ring in the manner of an iris aperture is provided in the case of a circular braiding machine. Here too, all segments can only be adjusted simultaneously by the same angular increment. Therefore, it is also not possible for the unilaterally changing cross-sectional shape of a braiding core to be followed with this braiding ring.
It is an object of the present invention to provide a braiding ring that is composed of individual segments such that even complex braiding core geometries can be braided with high quality, using said braiding ring.
This object is achieved by a braiding machine, in particular a circular braiding machine, for braiding a braiding core that is fed in a permanently continuous manner, having a cross section that varies in the longitudinal direction of the braiding core, having at least two braiding thread spools and having a braiding ring that is disposed between the braiding thread spools and the run-on point of the braiding threads onto the braiding core. The braiding threads are guided over the internal surface of said braiding ring, and the latter is composed of a plurality of adjustable segments, wherein each adjustable segment of the braiding ring has a dedicated adjustment installation. Each adjustment installation is actuatable independently of the adjustment installations of the other segments.
On account of each segment of the braiding ring being able to be adjusted individually by an arbitrary increment, the braiding rings can be adapted in an optimal manner even in the case of complex braiding core geometries such as rectangular braiding cores having a maximum ratio of W/H=3/1, oval braiding core cross sections, or abrupt and/or unilateral changes in the cross section of the braiding core cross section etc., and the braiding threads or braiding fibers, respectively, can thus be guided in an optimal manner. On account thereof, it is possible for the positionally correct run-on point of the braiding threads onto the respective braiding core area to always be guaranteed. Above all, the clear spacing between the internal surface of the braiding ring and the run-on point can also be minimized at all times. The braided structure across the length of a braiding core having a complex geometry thus becomes substantially more consistent, or can be influenced in a targeted localized manner such that the adaptation of the braiding ring shape is performed during braiding, respectively.
It is indeed known from DE 10 2011 006 647 A1 for variable opening widths having a closed border to be implemented during braiding. Individual segments that are mounted so as to be unilaterally rotatable to each are provided with a dedicated drive by way of linear guides. However, here too, all segments are simultaneously swiveled about the same angle. By contrast, the present invention differs therefrom in that each segment herein can be moved independently of the other segments.
These advantages can be achieved in a particularly simple manner by way of a further aspect of the invention, wherein the braiding ring is subdivided into six segments. The six segments are disposed in an alternating manner in two parallel planes. The six segments form the shape of a hexagon. In order for there not to be any gap between the individual segments, in each case two successive segments are disposed in different planes. Thus, three segments are disposed in a first plane, and the other three segments are disposed in a second plane that is parallel with the first plane.
Advantageously, the segments at the one end of the former are rotatably mounted, wherein the other free end overlaps the articulation point of the subsequent segment. On account thereof, it is ensured that no gap can be formed between the segments that can lead to damage to the braiding threads or to a fault in the braided product, respectively.
The segments can be embodied so as to be straight, or curved with identical or dissimilar curvature radii.
A further aspect of the invention is characterized in that each segment has a longitudinal groove in which the adjustment installation engages in a displaceable manner. This describes a space-saving construction of the fastening of each adjustment installation on the associated segment of the latter. The mass of the segments is moreover reduced on account of the longitudinal groove, such that a rapid and force-saving adjustment is possible.
In order for the adjustment installation to be able to be retained in the longitudinal groove without additional fastening devices, the longitudinal groove has an indented peripheral region such that the adjustment installation cannot be released upwardly from the longitudinal groove.
Two alternative adjustment installations are also described. It is expedient herein for, in each case, opposite segments of the adjustment installation to be disposed on one common effective line, independently of the construction mode of said segments.
The refinement of the invention wherein all adjustment installations are mounted on one common retention ring describes a simple device-related construction of the braiding ring arrangement according to the invention.
On account of a design embodiment wherein every second segment and the respective adjustment installation associated with said segment is fastened to the retention ring by way of a spacer sleeve, all segments can be disposed on one side of the retention ring. Of course, it is also possible for one part of the segments to be disposed on the one side, and for the other part of the segments to be disposed on the rear side of the retention ring.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.